1968 BSA Thunderbolt 650cc - going home, or NOT (part 1)

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1968 BSA Thunderbolt 650cc - going home, or NOT (part 1) 5
1968 BSA Thunderbolt 650cc - going home, or NOT (part 1)

Just when you think it’s safe to return a motorcycle to it’s owner..

Applying the final steps to Tim’s BSA before returning it and it won’t start. There’s a decent spark at each plug but both are bone dry, suggesting that fuel isn’t getting through to the cylinder heads. I’m assuming that one of the jets or passages is blocked from the bike being stood for several months.

Removed the carburetor and find another little issue with the manifold being a little warped. This shouldn’t affect the starting but could have explained a little rough running. So straightened the manifold out by rubbing down with glass paper and then thoroughly cleaned the carb, jets and other passages and used compressed air to clean everything out.

Just looking over the bike to refit the carb, I notice that the stator wires are in bad shape. I knew that they were brittle but they seemed okay when wiring the bike. One bullet had already come off, possibly while removing the carb or the air filter. The other stator wire simply broke when I twisted it.

So the next job will be to remove the stator and replace / solder the stator wires and refit them to the bike.

Download — 1968 BSA Thunderbolt 650cc - going home, or NOT (part 1)

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💬 Comments on the video

Wish I lived near you, I could spend hours learning and tinkering with those British bikes.
Oh, and about one job leading to another, I coined and often say "every solution causes another problem" I think I should make T-shirts that read that. It comes from years of doing things with engines and what have you only to find the simple fix always leads to something else.

Author — Wooley689


Bit late to the party--just been binge-watching your stuff on and off all day and evening, commencing with your superb and extensive 'Norton Atlas Project – Shep' series, for which I cannot thank you enough. As far as this BSA's Amal carb, unless I'm mistaken it seems to have one of those craptastic original white plastic float needles. They're too light to do the job properly, and because they cause all sorts of mysterious fuel delivery issues, most have long since been replaced with the heavier and better brass viton-tipped ones. In fact, it's pretty rare to even see the plastic needles still in use. As for the flange, I usually give the rubber O-ring a very light smear of RTV Red silicone gasket goo, and that seems to keep her from wheezing.

Author — BilgemasterBill


Great video. I bought a 68 Royal Star October 2016. I will be following gyour vids to help me. I m pretty handy and have a few old Brit bikes, and have done quite a bit of work on them but any extra learning is always good. I rebuilt the kickstarter and put in a Wassel ignition. New Wipac dimmer and horn switch. It has a kill button on it but haven't figured out how to wire it up with the wassel yet. Any ideas?I also have a billet sump plate the original has had 3 of the 4 bolts removed (probably stripped) and screws put in. I think I will need to get a shop to drill the holes and helicoil it for new bolts to mount the plate. Starts okay but I think next winter I will completely overhaul fuel system including relining tank. Have you adjusted the clutch on these bikes? I followed the MMM Nicholson book instructions and I think its too tight now. But cable adjuster is at max if I leave the center screw adjuster slightly slack and tighten the nut.

Author — kevin johnson


Hi there, I have a question for you about a BSA... I bought a 69 Lightning and am in the process of restoring it, I have hit a snag that I can not figure out... when I try and hook up the battery it instantly blows the 17 amp glass fuse that is in line with the positive terminal, I have checked all over the bike for a short and cant find anything... any help would be greatly appreciated because I am at my wits end...

Author — Ryan Chelberg


You will never be bored with a British bike in your garage.

Author — Townsey


Hi Mike, Good to see you found the problem why no gas is being sucked into the engine the air-lead on the carb, I had a bad running problem on my old 650 Bonnie!! that was down to air leaks on the carbs too.

Is the inlet port part covered by a gasket under the heat gasket or something or is it the camera angle ?

Author — trident watch